Sea Otters

Back From the Brink

A sea otter floating on the surface of the ocean
Image Source: Michael L. Baird

Last week, Alex and I were in Birmingham and we decided to visit the National SEA LIFE Centre. Originally, we weren’t even scheduled to go there, but then we learned that it had recently become home to the UK’s first – and only – pair of sea otters. Upon realising that there were only three other collections in the whole of Europe to house these amazing animals and that the Birmingham SEA LIFE Centre was probably the only place we were likely to see them any time soon, we simply couldn’t resist squeezing a visit into our already-packed schedule.

The two Alaskan sea otters at Birmingham – Ozzy and Ola – were both rescued when they were pups. Orphaned, underweight and dehydrated, they were cared for at the Alaska SeaLife Centre, a public aquarium and marine mammal rehabilitation centre. This facility aims to treat and return injured animals back into the wild wherever possible, but Ozzy and Ola were deemed un-releasable. After a gruelling guardianship application process that took over two and a half years to complete, the Birmingham SEA LIFE Centre was finally granted a permit to house the two sea otters by the United States Fishing & Wildlife Service (USFWS) at the end of 2019.

Fantastic Fur

Most otters return to land to sleep and nurse their young, and some species even spend significant time hunting there, too. But the sea otter is almost completely aquatic. Although it can certainly walk on land, it tends to lumber around like a cross between a seal and a fat dog. In fact, it is more than capable, if it so desires, of never leaving the water once in its life – it feeds, sleeps and mates in the ocean, and can even give birth there. This means that in many ways the sea otter is more aquatically adapted than seals, which must haul themselves up onto a beach or the ice to have their young.

The sea otter is considerably larger than one would probably imagine from their photographs or appearances in nature documentaries, and although I already knew in advance that it was the heaviest member of the mustelid family (albeit slightly surpassed in length by the giant otter, a freshwater species from South America), I was still surprised by the size of the animal when I finally saw a sea otter in real life.

A sea otter floating on the surface of the ocean
The only member of its genus, the sea otter is so different from other mustelids that, even as recently as 1982, some scientists believed it was more closely related to seals than to other species of otter.
Image Source: PxHere

But although it is a heavyweight among the mustelids, the sea otter is nonetheless one of the smallest marine mammals overall (only its relative, the marine otter, is smaller). This means it needs very effective insulation to reduce heat loss. Most marine mammals use insulating blubber, but the sea otter has a thick, waterproof coat of fur instead. This fur is the densest of any mammal – up to 150,000 strands of hair per square centimetre, and up to 800 million altogether (a typical human, for comparison, only has around 100,000 hairs on their entire head). Altogether, this lustrous coat of fur represents about a quarter of the animal’s weight.

The sea otter’s coat is made up of two layers: an inner insulating layer of very short, soft underfur that traps air to keep the animal warm, plus an outer water-repellent layer of long guard hairs. Each hair is covered in tiny barbs that help mat them all together so tightly that, even though the animal spends almost its entire life in the sea, water cannot penetrate to the skin. But as the ability of this fur to repel water depends on utmost cleanliness, the sea otter must spend hours every day floating at the surface, taking advantage of its loose skin and an unusually supple skeleton to groom every part of its body.

A sea otter grooming itself on the surface of the ocean
Sea otters spend up to six hours a day maintaining their pelt, vigorously grooming it and blowing air into it to increase its thermoregulatory properties. This makes the sea otter so buoyant in the water that it sometimes carries rocks when it dives, in the same way a human diver might wear a weight belt.
Image Source: Michael L. Baird

Despite its thick fur, though, a sea otter still burns huge amounts of energy just keeping warm. An adult must consume around a quarter of its body mass in food every day, and a lactating female must double that energy intake. It dives underwater to collect its food – usually fish, mussels and snails – and it is the only marine mammal that catches fish with its forepaws rather than with its teeth.

Under each foreleg, a sea otter has a loose pouch of skin that extends across its chest. In this pouch (usually the left one), the animal stores food that it has gathered during its dive so that it can be eaten when it returns to the surface. If it catches a large shellfish that it cannot prise open with its teeth and claws, the sea otter will use tools instead. Floating on its back at the surface with its food on its belly, it uses a small rock held in its paws to smash open the shell to reach the nutritious flesh inside. This makes the sea otter one of just a handful of non-primates to use tools (others include dolphins, crows and octopuses). It often holds on to its favourite tool by tucking it into its armpit pouch when diving.

Two sea otters sleeping on the surface of the ocean, holding paws
Sea otters are kept afloat by their naturally high buoyancy. They sometimes sleep on the surface of the water holding paws, as the pair in the image above are demonstrating.
Image Source: Joe Robertson

Saving Sea Otters

The thick, luxurious fur of the sea otter keeps it warm and dry in the cold seas, but it was almost the animal’s undoing. Around 250 years ago, the population of sea otters was thought to number between 150,000 and 300,000 individuals, spread along North America’s western seaboard from Mexico to Alaska, and across the Pacific to Japan. But then people began to relentlessly hunt these seafaring members of the weasel family for their fur. Considered the most valuable pelt in the world, each one was the equivalent of a seaman’s normal wage for the entire year. In 1803 alone, around 17,000 sea otters were slaughtered for their coats, as the sought-after fur reached the heights of fashion.

As you can imagine, this unregulated exploitation had a devastating effect on the sea otter population. In 1911, when fewer than 2,000 individuals remained on the entire planet, Russia, America and Britain (on behalf of Canada) agreed on the total protection of the species throughout the North Pacific. This multi-national treaty – one of the first global conservation initiatives of its kind – helped bring the sea otter back from the brink of extinction. Gradually, numbers have increased from an all-time low at the turn of the 20th century to well over 100,000 today.

But sea otters aren’t out of the woods yet. Intensive commercial fishing creates competition for sea otters, and entanglement in abandoned fishing gear poses a big threat. They are also particularly vulnerable to oil spills. If their insulating fur becomes soaked in oil, it loses its ability to retain air and the animals can quickly die from hypothermia. The Exxon Valdez oil spill of 24 March 1989, which left Prince William Sound in Alaska smothered in 11 million gallons of crude oil, killed almost 4,000 sea otters – around 90% of the Alaskan population at the time. Even today, lingering oil in the area continues to affect these animals.

Sea otters primarily live in and around kelp forests, usually no more than a kilometre from shore. They may even wrap themselves in kelp fronds when resting on the surface to stop themselves drifting out to sea or into rocks.
Image Source: NOAA’s National Ocean Service

Ozzy and Ola arrived at the Birmingham SEA LIFE Centre in early 2020, after a 5,000-mile journey from their former holdings at the Alaska SeaLife Centre. From there, they went into quarantine and began to settle into their new temperature-controlled enclosure, which is designed to replicate their natural habitat and give them a safe sanctuary for the rest of their lives. As part of a pioneering education and conservation project, these two animals, as the first and only ones of their kind in the UK, have a crucial role to play in the global mission of making sure sea otter numbers continue to recover.

Seeing these two frolicsome animals splashing around and playing with each other at such close quarters was definitely the highlight of our visit to the SEA LIFE Centre. Their incredibly furry appearance, coupled with their whiskered faces, their human-like grooming skills, and their adorable tendency to use their bellies as a picnic table make sea otters the very definition of ‘cute’. I defy anyone who has seen these remarkable animals in real life not to become completely enamoured by them. I know we certainly are.


  • Jason Woodcock

    With a background in conservation and animal behaviour studies, Jason's passion lies in the natural world. He adores all things nature and enjoys nothing more than spotting rare and interesting species out in the wild. He has also worked in a zoo and knows plenty about keeping the animals inside our homes healthy and happy, too.

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